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DESIQN <br /> • General <br /> The sedimentation and drainage control structures have been designed and <br /> eonstr.ycted .in accordance with Colorado Mined Land Reclration Board requirements <br /> and with Office of Surface Mine regulations (Federal Register, March 1979) <br /> General design criteria that apply to all sedimentation ponds, dams <br /> and appurtenant works,ie spillways and outlet works; are described herein. <br /> Pand capacities have been determined by-storage of the entire sediment <br /> and the entire runoff vol um m generated by <br /> whim~ generated over 3-year period <br /> a 10-year 24-hour design storm. (Type I!, SCS) <br /> Emergency spillways have been desi&ned to permit 100 per cent peak discharge <br /> of a 25-year 24-hour design Type II Storm (SCS) . <br /> All outlet works will be 6 inch diameter gated corrugated metal pipe that <br /> are located above the m :Kin Im sediment storage pool. <br /> Fzbx�,T�t fill sections are to be- constructed to a density that is 95 <br /> per cent of the standard proctor density within 2 per cent of the cptin n <br /> moisture content in accordance w/AST11 D-698. Subgrade soils must be stripped <br /> and cleared prior to fill placeret. ' Native soils on steep slope crust be benched <br /> before fill plaYrat. Fill must be placed in horizonfial lints not less than <br /> S inches or in excess of 10 inches coapacted thi.cl—mess. Rock particles larger <br /> than 6 inches must be rived or broken up before placement and can <br /> pacted, veg- <br /> etated or ripraped as required. <br /> All discharge points for spillways and outlet wrk rust be protected by 1 to <br /> 2 feet thick riprap layer. The sized ripYap must range from 3 inches to 12 inches <br /> in diameter. Riprap sand bedding 1 foot thick shall be placed prior to rock fill <br /> PIaceme��t. <br /> r rgency spillways shall be const-ruscted of galvanized steel, 16 gauge thick- <br /> ness or equal. Galvanized steel or equal altoff collars 4' by 4' shall be placed <br /> on 15' centers. <br /> -4-4 6 <br />